An embodiment relates generally to detection of a wet road surface using noise measurements.
Precipitation on a driving surface causes several different issues for a vehicle. For example, water on a road reduces the coefficient of friction between the tires of the vehicle and the surface of the road resulting in vehicle stability issues. Typically, a system or subsystem of the vehicle senses for precipitation on the road utilizing some sensing operation which occurs when the precipitation is already negatively impacting the vehicle operation such as detecting wheel slip. Under such circumstances, the precipitation is already affecting the vehicle (e.g., wheel slip), and therefore, any reaction at this point becomes reactive. That is, to detect precipitation using wheel slip, the vehicle must be active in the unwanted condition (e.g., wheel slip) in order to detect it. As a result, such a system is reactive instead of proactive.
Another example of how precipitation negatively affects a vehicle is water ingestion into the air vents of a vehicle which leads to water ingestion into the engine. Some vehicles utilize supplemental air vents exterior of the vehicle body, such as air intake hood scoops, to reduce the temperature of the air supplied to the engine and to increase the density and pressure of the air thereby providing an improvement in power from the engine. The air intake hood scoop allows air to be admitted to the engine forward of an air cleaner or fuel injector. However, any precipitation entering the air intake hood scoop results in water ingestion directly to the engine which degrades engine performance. Precipitation into the air intake hood scoop could be the result of rain directly falling into the air intake hood scoop or may be the result of puddled water on the road surface being picked up and sprayed rearward by vehicle ahead of a driven vehicle. Therefore, it would be pertinent to identify a wet road surface prior to precipitation building up on the road surface where it can negatively affect the vehicle.